Abstract

Throughout the Pliocene and Pleistocene, a hierarchy of sea-level fluctuations alternately flooded and exposed the Great Bahama Bank, controlling its sedimentary evolution. The persistent rhythm of sea level is best shown in the upper Pleistocene to Holocene section in which 10 cycles of sea-level rise and fall are identified in core borings on the lee side of the bank. The same number of sea-level oscillations is indicated within the Brunhes chron of the deep-sea oxygen isotope record. In the Bahamas, sea-level oscillations are inferred from meter-scale parasequences of shallow-marine carbonates, interpreted largely as transgressive and highstand deposits, sandwiched between discontinuity horizons interpreted as subaerial-exposure horizons that developed during lower sea level. Subaerial exposure shifted from being largely restricted to the platform interior during the late Pliocene (Olduvai chron), to occurring across the entire lee side of the platform at the beginning of the Brunhes chron. This change on the platform is highly suggestive of the deep-sea oxygen isotope proxy of sea level which indicates a fundamental paleoclimatic shift at approximately the same time. Despite dating limitations, results from the Bahamian cores can be used to push the calibration of the sea-level record back to the late Pliocene.